Tuesday, February 26, 2013

Πάντα ρεί - once more on the (right) fluids

Yet another manuscript evaluating fluids for IV replacement was published in JAMA this week underscoring the importance and controversial nature of the topic. A large meta-analysis involving 10,868 patients from 38 trials showed that hydroxyethyl starch (HES) was associated with an increased risk of mortality and renal failure (RR 1.27; 95% CI 1.09 - 1.47). Of note, a recent large trial published in the NEJM in 2012 did not show an increased mortality but more patients who received resuscitation with HES were treated with renal-replacement therapy.

HES is mainly used by anesthesiologists and surgeons and has the potential advantage of decreasing the amount of total administered volume and sustaining intravascular volume for longer periods of time. The discussion about mortality and renal failure associated with HES has been going on for a long time, as has the discussion about the relative benefits of colloids vs. crystalloids. Despite the lack of strong evidence of superiority of HES over crystalloids, the clinical use has been increasing - even with the associated higher cost and safety concerns.

A major drawback for the supporters of HES was the realization that one of the leading authorities in the field and major proponent of HES, Joachim Boldt, has conducted one of the biggest cases of fraud in anesthesia with “false data published in at least 10 of the 91 articles examined, including, for instance, data on patient numbers/ study groups as well as data on the timing of measurements“. 80 articles have been retracted because the research was deemed unethical. A Cochrane review from 2012 did not find a significant difference in mortality even when the fraudulent studies were excluded. However, the current meta-analysis not only excluded the studies by Boldt, but also included 3 trials published in 2012 contributing more than half of the patients to the collective examined, thereby adding more weight to their analysis over prior ones. There was no difference in mortality when the Boldt papers were included in the analysis.

Side effects of HES mainly occur in the kidney but the exact pathophysiology of AKI associated with HES is unclear. Vacuolization as an injury pattern can be observed as discussed in an earlier post in this blog. In vitro HES showed a dose-dependent decreased viability of HK-2 cells (human immortalized proximal tubular cells) after incubation with HES130/0.4. A necropsy study suggested HES accumulation in the kidney might cause toxicity. 

What can we learn from this? Rigorous analysis and ongoing discussion and evaluation of data are of crucial importance in Medicine and scientific fraud, driven by motives such as recognition and money can cause data to shift to the wrong direction. There does not seem to be a major advantage of using HES over crystalloids and data on mortality and renal failure are tied between no difference and increased mortality/AKI in the HES group. From my perspective there seems to be no indication to use HES and this might be better for the kidney.

Posted by Florian Toegel

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